Could this be the most ambitious car that BMW has ever produced? Just imagine when the idea was conceived – a lightweight, £100,000 supercar made from exotic materials, but powered by a three-cylinder engine, and emitting less than 100g/km of CO2. Can you really have your cake and eat it?

BMW seems to think so, and five years after the original concept was revealed, the production i8 is even faster, even more high-tech and even more efficient than when it was conceived. Using a combination of a tiny petrol engine, high-voltage lithium-ion batteries like the one in your laptop, and a powerful electric motor, the i8 is a plug-in hybrid that has been designed to be just as exciting to drive as it is kind to the environment.

The only cars on the market that do the same job are built by Porsche and McLaren, and cost close to a million pounds each, so an asking price of £96,385 (after the £5000 government discount) seems almost affordable.

What is the 2014 BMW i8 like to drive?

It takes only a few miles to realise the i8 is a totally different kind of supercar, and the first thing to alert you to that fact is the absence of noise when starting-up. Something this fiendishly complicated should be difficult to drive, but in fact it’s just as easy to operate as its little brother, the i3.

Push the start button and a chorus of sci-fi-like bleeps and a soft whirr from the electric motor are the only noises that greet you. The i8 always sets off in its default ‘Comfort’ driving mode (one of five), which is designed to maximise fuel efficiency by using the best mix of electric and petrol power based on your driving style, route, and even the traffic on the road.

The 129bhp electric motor draws its power from a battery pack that runs down the spine of the car, and sends it to the front wheels via a two-speed automatic gearbox. You can use this power source alone by choosing 'e-drive' mode, which limits your top speed to 75mph, and gives you a range of around 22 miles.

Bury your right foot all the way to the floor, or flick the gearlever left to activate ‘Sport’ mode, and the dials turn from blue to orange as the 1.5-litre engine wakes up. Despite the diminutive engine size, by using a two-stage turbo BMW has squeezed 228bhp and 236lb ft out of it, all of which gets sent to the rear wheels, through a six-speed automatic ‘box.

In this mode, it sounds like there is a huge V6 sat behind you, not a three-cylinder supermini engine. It growls pleasingly as you accelerate, getting louder as the revs rise, and the car even blips the throttle on downshifts, for even more drama. The two power sources working together transform the i8 into a proper four-wheel drive supercar, bringing 0-62mph up in just 4.4 seconds, with a top speed of 155mph.

Despite having essentially two engines, the smooth, linear power delivery means the i8 is a surprisingly refined cruiser. When you’re in a high gear the engine fades into the background, removing the sensation of speed, so you can be going very fast point-to-point, without really noticing.

It's much more than just a cruiser, though. The front and rear tracks are wider than those on the BMW M3, and there's a decent amount of grip, even in tight corners or on rain-soaked roads. The four-wheel drive system sends extra power to the rear wheels on the entry of corners for better turn-in, then reverts to a 50:50 split for better traction once you're past the apex.

Ultimately though, the i8's front end washes wide sooner than say, a Porsche 911's, and its steering is oddly light – especially in Comfort mode. Even in Sport there’s a dead spot around the straight-ahead, which means you’re not always aware of what the front wheels are doing.

That said, throw it into a corner and there’s virtually no body roll, with the i8 changing direction with little sensation of the weight of the batteries pulling you around or harming agility – a first for any hybrid car we've driven.

This superb agility is down to the i8’s low weight. It tips the scales at 1.5 tonnes, nearly 100kg less than an Audi R8 with a V8 engine, thanks to its use of carbonfibre, mixed with plastic panels and an aluminium chassis.

The ride could be better, though. Despite the standard adaptive dampers, the i8 can get a little bouncy over bumps, while scruffier surfaces cause it to jitter over small imperfections.

The standard 20-inch wheels also generate a fair amount of road noise, which resonates around the cabin. This problem is no worse than in the i8's main rivals, though – including the Porsche 911.

What is the 2014 BMW i8 like inside?

Swing open the i8’s scissor doors, and you’ll find a pared down, futuristic cabin. The driver and front passenger sit low to the floor of the car, on slender leather seats. These slide and recline electrically, so it only takes a few seconds to find the ideal seating position.

Getting in is a little tricky though. There's a high sill to negotiate, and you need to stoop to avoid cracking your head on the grab handles in the door or the low roof. The narrow aperture makes getting into the rear even trickier, so make sure whoever offers to travel back there is either small already or possesses the ability to fold themselves in half.

Visibility is surprisingly good, though – outstanding by supercar standards. The large rear screen gives an excellent view out of the back, and the car never feels too wide to manoeuvre through traffic, or thread down a narrow rural road.

Cabin quality is good. but no better than most of BMW’s other models, so for a car that costs close to £100,000, some buyers might find a few of the plastics and switchgear a bit disappointing. It's short of storage, too – there are no door pockets and only a tiny glovebox and some shallow trays for storing loose items.

The ambient lights are a nice touch, though, and there are two 8.8-inch screens; one displays your speed, revs, and remaining level of charge, the other shows the sat-nav, infotainment and other auxiliary systems, and uses the brilliant iDrive interface that features in most other BMWs. A head-up display projects key information onto the windscreen, so you can keep your eyes on the road. You can also open or close and lock the doors and windows via an app on your smartphone, which also tells how much charge is left in the battery, and can remotely pre-condition the climate control to warm-up or cool-down the cabin.

Every i8 comes with heated leather seats, sat-nav, adaptive dampers, parking sensors, a multi-function steering wheel, 20-inch alloys and LED headlights. There are a few choice options though, including more opulent leather, a high-end Harmon Kardon sound system, and (from November) Laser beam headlights, which mimic daylight and which can illuminate up to 600 metres down the road.

The boot is pretty minute, with just enough room for a soft bag (or two backpacks) and a fabric parcel shelf, but that’s your lot. However, since the rear seats aren't really suitable for adults, you can use this space for extra storage.

Should I buy one?

The i8 represents a brave, groundbreaking move by BMW to bring sports cars into the modern age.

It looks and feels like nothing else in this class, and manages to be every bit as exciting to drive as it is to stare at. If you're after the last word in dynamic poise, you'd be better off with a Porsche 911, but the i8 is still a quick, grippy sports car that's capable of near 40mpg in the real world.

It also emits just 49g/km of CO2. That makes it (as a company car at least) by far the cheapest sports car on sale, because it qualifies for the 5% band of company car tax. We can see more than a few company directors deciding to conduct their commute in the latest ‘i’ model.

With only a few hundred planned this year, exclusivity is virtually guaranteed, too, and with a total range of over 300 miles, and a three-quarter recharge time of two hours (from a dedicated high voltage wall box) it’s also a lot more useable than an i3.

The i8 is a superb achievement, then. It takes a huge amount of incredibly complicated technology and turns it into something desirable, easy to drive and easy to live with.